1. Field of the Invention
The present invention relates generally to direct broadcast satellite systems, and in particular, to a Ka-band and Ku-band outdoor unit using a frequency selective surface on a single-offset dish antenna.
2. Description of the Related Art
Satellite broadcasting of communications signals has become commonplace. Satellite distribution of commercial signals for use in television programming currently utilizes multiple feedhorns on a single Outdoor Unit (ODU) which supply signals to multiple Integrated Receiver-Decoders (IRDs) on separate cables from an integrated multiswitch. Additional IRDs can be serviced with external cascaded multiswitches.
In a satellite broadcasting system, a service provider may broadcast video programming signals from transponders on multiple satellites in multiple different orbital slots. These orbital slots are typically located at 101 West Longitude (WL), 119 WL, and 110 WL, also known as Sat A, Sat B, and Sat C, respectively, but can be at other locations as available. The FCC (Federal Communications Commission) allocates transponders on the various satellites at the orbital slots for use in broadcasting television signals.
These satellites typically broadcast in the Ku-band of frequencies, typically between 12.2 GHz and 12.7 GHz. Additional satellites are also deployed at other orbital slots, and are compatible with the already-deployed satellites used within the system. These newly-deployed satellites typically broadcast in the Ka-band of frequencies, typically between 18 and 20 GHz. The additional satellites can be placed on-orbit at any location, but currently, the locations are at 99 WL and 103 WL. Additional satellites may be placed at other locations, such as 101 WL.
Although additional ODUs can be installed to receive the Ka-band frequencies, installation of an additional ODU at a given location may be difficult, as well as costly. Further, multiple ODU installations will be difficult to connect to existing systems, because of potential additional cable runs as well as possible interference with existing equipment.
It can be seen that there is a need in the art for an ODU that can receive both Ka-band and Ku-band signals. There is also a need for a method that takes into account the position of the satellites that are transmitting these frequencies, as well as designing the ODU to maximize the signal strength from the Ka-band.